(Photo contributor: Binita R. Shah, MD)
*The authors acknowledge the special contributions of Binita R. Shah, MD, to prior editions.
Kawasaki disease (KD; also known as mucocutaneous lymph node syndrome) is a self-limited, medium-vessel vasculitis of unknown etiology. Prompt diagnosis and treatment prevent complications of KD, which include endothelial cell injury mainly in medium-sized arteries (in particular, coronary arteries) and systemic inflammation in multiple organs during the acute febrile phase of the disease. The risk of coronary artery aneurysm (CAA) is decreased from 25% to 4% by the timely administration of IV immunoglobulin (IVIG).
KD occurs in all ethnic groups; however, incidence is highest in Asians (in particular East Asians) and Pacific Islanders and is more common in boys compared to girls. In the continental United States, the incidence of KD is about 25 per 100,000 in children <5 years old. Clinical and epidemiologic features strongly implicate an infectious etiology, although no specific infectious trigger has been identified. Diagnosis of KD is largely based on clinical criteria, as summarized in Table 12.1, and exclusion of other similar disease presentations. Clinical features include extreme irritability, aseptic meningitis (50%), urethritis (sterile pyuria, 70%), hepatic dysfunction (40%), hydrops of gallbladder, diarrhea, vomiting, abdominal pain, arthritis or arthralgia (knees, ankles, hips), uveitis, pneumonitis, testicular swelling, peripheral gangrene, erythema, or induration at bacillus Calmette-Guérin (BCG) inoculation site.
KD should be considered in any child with prolonged unexplained fevers, but particularly in infants <6 months of age with fevers and irritability. Approximately 10% of children who develop CAA never meet criteria for KD. Clinicians should have a high index of suspicion because established clinical criteria do not, unfortunately, reliably identify all children with KD.
Kawasaki Disease. A 3-year-old child with a history of high fever of 6 days in duration associated with diffuse erythematous maculopapular rash, red lips, and bilateral conjunctival injection. (Photo contributor: Binita R. Shah, MD.)
Emergency Department Treatment and Disposition
Obtain CBC (normal to elevated WBC count with a predominance of polymorphonuclear leukocytes and normocytic anemia), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP; usually elevated), liver enzymes (elevated with hypoalbuminemia), and urinalysis (sterile pyuria and proteinuria). Platelet counts are usually normal at onset of disease. Significant thrombocytosis (platelet count up to 1 million) occurs in the second week of illness and may indicate a longer duration of symptoms.
Be mindful of thrombocytopenia, anemia, or hyperferritinemia (>1000 ng/mL) because this may indicate early macrophage activation syndrome (see page 589), an emergent complication of KD. If clinically indicated, perform a lumbar puncture; CSF will show mild pleocytosis with normal glucose and usually normal protein. Obtain chest radiograph to look for cardiomegaly and an ECG for evidence of myocarditis, pericarditis, or arrhythmias. Admit patients with clinical diagnosis of KD or suspected incomplete KD (see page 567), for continuous cardiac monitoring and to initiate treatment with IVIG (2 g/kg; given as a single dose over 8–12 hours) and anti-inflammatory dose aspirin (80–100 mg/kg/day divided in 4 doses; given until patient is afebrile for at least 3–4 days) ...